Grinding apparatus



May 26, 1959 H. c. ELSE GRINDING APPARATUS Filed March 7, 1957 IN VENTOR.

BY find/MAM .GRINDING APPARATUS Harry C. Else, Pittsburgh, Pa.

Application March 7, 1957, Serial No. 644,522

4 Claims. (Cl. 51-168) This invention relates to apparatus for grindingthe surfaces of substantially fiat workpieces, such as metal slabs andthe like.

High carbon steel, stainless steel and many spec1al alloy slabs have tobe skin ground to remove surface defects before they can be rerolled,hammered or forged. This grinding is generally done by a grinding wheelturmng on an axis extending in the direction in which the work piece orwheel is moved. It will therefore be seen that if the grinding is veryshallow, only a very narrow strlp will be ground during each pass overthe work, so there is a tendency to grind more deeply in order to covera wider path during each pass. Deep grinding has the d1sadvantage ofleaving a feather-edge ridge between passes, which then has to be groundto remove it to prevent possible spoiling the surface of the materialwhen the slab is reworked. Also, deep grinding removes too much materialwhen expensive alloys are being ground. If the axis of the grindingwheel extends transversely of the grinding path, a wide shallow path canbe ground by using a wide grinding wheel. However, such a wheel is notpractical because under the necessary high pressures and high speeds,the wider the wheel, the more heat it retains and the hotter it gets. Asthe wheel heats up, it tends to clog up and glaze on its surface. Thismeans that either grinding becomes inefficient or else there has to be ashut-down while the wheel is dressed.

It is among the objects of this invention to provide grinding apparatus,with which a wide path can be ground along the surface of a metal slabduring each pass without grinding'deep and without overheating thegrinding wheel.

According to this invention, a rotary shaft extends diagonally across abed for a substantially flat workpiece. Means are provided for effectingrelative movement between the shaft and bed lengthwise of the bed.Rigidly mounted on the shaft is a plurality of grinding wheels disposedin axially spaced relation so that they will grind parallel paths alongthe workpiece. The spacing of the wheels is such that the paths willoverlap along their adjoining edges and will have a combined widthgreater than the width of the single path that would be ground to thesame depth by the same wheels if the shaft extended lengthwise of thebed. To hold and position the Wheels on the shaft, a pair of spaced hubsmay be slidably mounted on the shaft in engagement with the oppositesides of each wheel. Each hub has an annular shoulder projecting intothe adjoining wheel to support the wheel. One of the outer hubs ispositively rotated by the shaft. The two inner hubs are held apart byspacing means, and the spacing means and hubs are all forced toward oneanother by means mounted on the shaft, whereby to clamp them together.The spacing means and inner hubs are provided with interengaging socketsand laterally projecting pins to hold them against rotation relative toone another.

The preferred embodiment of the invention is illustrated in theaccompanying drawings, in which:

United States Paten' o v PatentedM f 9 Fig. 1 is a fragmentary plan viewof a pair ofgrinding wheels grinding a slab on a bed; I

Fig. 2 is an enlarged axial section through the wheels and theirsupports; and I i Fig. 3 is a reduced cross section taken on the lineIII- III of Fig. 2.

Referring to Fig. 1 of the drawings, a substantially fiat workpiece 1,such as a thick metal slab is supported by a suitable bed beneath a pairof grinding wheels 3 and 4. The wheels are mounted on a rotary shaft 5that is driven at high speed by an electric motor (not shown) in awell-known manner. Any suitable means is provided for reciprocatingeither the shaft or the bed in a direction lengthwise of the slab. Thedrawing indicates that it is the bed that is moving lengthwise to carrythe slab in the same direction beneath the grinding wheels. I

It is a feature of this invention that the rotary shaft extendsdiagonally across the bed, and that the grinding wheels are spaced apartalong the shaft a predetermined distance, depending on the angle of theshaft relative to the bed. The wheel spacing and the shaft angle shouldbe so related that the adjoining edges of the two paths ground along theslab by the wheels will overlap, but only slightly. At the same time, inorder to gain any advantage from this invention, the combined width ofthe two paths should be materially greater than the width of the singlepath that would be ground by the same wheels in tandem in case the shaftextended lengthwise of the bed. For the two paths to'overlap, each wheelmust grind on both sides of a vertical plane extending lengthwise of theslab through the axis of the shaft midway between the two wheels, buteach wheel should grind only a very short distance on one side of thatline if the widest possible surface is to be ground during each pass.

Even with only a 30 shaft angle, as shown in the drawings, the combinedwidth of the paths ground by the two wheels in one pass is 50% widerthan the path that would be ground if the shaft extended lengthwise ofthe slab, unless the slab were ground much deeper, which would beentirely impractical. On the other hand, if the shaft extendedtransversely of the slab at right angles to it, it would have to beprovided with a very thick wheel-to grind such a wide path. Awheel ofthat s ze would overheat and clog up and 'glazein a very short time. Byusing two narrow wheels spaced apart and disposed at an angle to thedirection of grinding, a wide path can be ground without grinding deepand without overheating the wheels. When the shaft is at a 45 angle tothe bed, the grinding wheels can be spaced even farther apart and astill wider area can be ground.

Each grinding wheel is spaced from the drive shaft, but is supported inproper position thereon, by a pair of hubs slidably mounted on theshaft. As shown in Fig. 2, the hubs 6, 7, 8 and 9 are provided withannular shoulders 10 that project into the wheels to center them on theshaft. The marginal portions of the hubs beyond the shoulders overlapthe sides of the wheels and frictionally engage them. To permit thewheels to be spaced farther apart than the hubs will space them,depending on their diameter and the angle of the supporting shaft,spacers are placed between the inner hubs 7 and 8. Each spacer is in theform of a disc 12, the marginal portion of which flares out, so that itsmaximum thickness is at its outer edge. Consequently, when the hubs anddiscs are clamped together, the greatest pressure is exerted at theirouter faces so that the hubs will be pressed tightly against the sidesof the grinding Wheels. The central portions of the discs are preferablyprovided with large circular shallow recesses 13 to space them from theinner hubs, which likewise may be provided with similar recesses. Theserecesses prevent any foreign particlesthat' may lodge between the discsand hubs from .holdingthem. apart.

The hubs and discs are clamped tightly together and against the wheelsby caps 14 and 15 engaging the outer hubs 6 and 9. The inner cap-14 iskeyed or'otherwise rigidly mounted on the shaft so'that' it will have toturn with it. The other: cap, is pressed against outer hub 9 by a nut 16screwed onto the projecting end of the shaft. To insure that rotation.of thedrive shaft willbe transmitted to the grinding wheels withoutslippage, hub 6 adjoining the inner cap 14 is provided withcircumferentially spaced pins 17 that project laterally into sockets 18in the cap. Preferably, there are three pins spaced 120 apart. Inner hub7 is provided with similar pins 19 that project into, sockets 20 in theadjoining disc 12, while the other disc has like sockets for receivingpins 21 projecting from the first disc. The pins on the second discproject into sockets 22 in the adjoining hub 8. Consequently, there canbe no rotation between the spacers and the inner hubs, and. as the hubswillv not slip on the rough surface of the grinding wheels, no rotationof the drive shaft will be imparted through the inner grinding wheel 3to the outer grinding wheel. It will be seen that either or bothspacerscan be removed in order to permit the two wheels to be placed closertogether, or additional spacers canbe used for spacing the wheelsfarther apart. Also, this invention is not limited to two grindingwheels, as more may be used when it is feasible to grind a still widerarea during each pass, or when narrower wheels are employed.

According to the provisions of the patent statutes, 1 have explained theprinciple of my invention and have illustrated and described what I nowconsider to represent its best embodiment. However, I desire to have itunderstood that, within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically illustrated anddescribed.

I claim:

1. In grinding apparatus having a rotary shaft extending diagonallyacross a bed for a substantially flat workpiece, a pair of annulargrinding wheels encircling the shaft and spaced therefrom, a pair ofspaced hubs slidably mounted. on the shaft in engagement with theopposite sides of each wheel, means connecting one of the outer hubs tothe-shaft for positive rotation thereby, each hub having an annularshoulder projecting into the adjoining wheel to support it, spacingmeans between the two inner hubs, and means mounted on the shaft forcingsaid spacing means and hubs toward one another to clamp them together,the spacing means and inner hubs being. provided, with interengagingsockets and. laterally projecting pins to hold them against rotationrelative to one another.

2. In grinding apparatus according to claim 1, said spacing meansincluding a disc encircling said shaft, the disc having its maximumthickness at its outer edge.

3. In grinding apparatus having a rotary shaft extending diagonallyacross a bed for a substantially flat workpiece, a pair of annulargrinding wheels encircling the shaft and, spaced therefrom, a pair ofspaced hubs slidably mounted on the shaft in engagement with theopposite sides of each wheel, means connecting one of the outer hubs to.the shaft for positive rotation thereby, each hub having an annularshoulder projecting into the adjoining wheel to support it, a spacingdisc mounted on said shaft between the two inner hubs, the marginalportion of the disc tapering toward the center of the disc, the discbeing provided with a plurality of sockets and laterally projectingpins, the inner hub adjacent said pins having pin-receiving sockets, theother inner hub having pins projecting into said disc sockets, and meansmounted on the shaft forcing said spacing disc and hubs toward oneanother to clampthem together.

4. In grinding apparatus having a rotary shaft extending diagonallyacross a bed for a substantially flat workpiece, a pair of annulargrinding wheels encircling the shaft and spaced therefrom, a pair ofspaced hubs slidably mounted on the shaft in engagement with theopposite sides of. each wheel, means connecting one of the outer hubs tothe shaft for positive rotation thereby, each hub having an annularshoulder projecting into the adjoining wheel to support it, a spacingdisc mounted on said shaft between the two inner hubs, the centralportions of the opposite sides of the disc being provided with circularrecesses, the marginal portion of the discs between said recesses andthe periphery of the disc being tapered inwardly, and means mounted onthe shaft forcing said disc and hubs toward one another to clamp themtogether, the disc and hubs being provided with interengaging socketsand laterally projecting pins to hold them against rotation relative toone another.

References Cited in the file of this patent UNITED STATES PATENTS1,491,515 Chase Apr. 22, 1924 1,722,724 Wegner July 30, 1929 1,878,415Legge Sept. 20, 1932

